1. Field of the Invention
The present invention relates to an ophthalmologic apparatus that executes a plurality of examinations on an eye.
2. Description of the Related Art
As an ophthalmologic apparatus that executes a plurality of examinations on an eye, an apparatus described in Japanese Unexamined Patent Application Publication No. 2007-282671 is known, for example. This ophthalmologic apparatus incorporates a first measuring part (an eye-refractive-power/corneal-shape measuring part) and a second measuring part (a tonometry part). These measuring parts are arranged next to each other in the vertical direction.
A working distance in tonometry is generally shorter than a working distance in eye-refractive-power measurement and corneal-shape measurement. For example, the former working distance is set to approximately 11 mm, and the latter working distance is set to approximately 35 mm.
In tonometry with a rather short working distance as described above, there is a risk that a nozzle for ejecting air comes in contact with a subject. The ophthalmologic apparatus according to JP-A 2007-282671 is configured to avoid contact with the subject by moving the tonometry part in a direction of the working distance (an anteroposterior direction with respect to the eye) when switching from the eye-refractive-power measurement, etc., to the tonometry.
Conventional tonometers also have various innovations to prevent contact with the subject. For example, Japanese Unexamined Patent Application Publication No. 2001-187024 describes a tonometer having a function of detecting the proximity to the subject and moving a measuring head.
Further, a tonometer disclosed on the Internet (URL: http://www.topcon.co.jp/eyecare/pdf/ct—90a.pdf) as a non-contact type tonometer CT-90A by TOPCON Corporation in an online catalogue (retrieved on Feb. 6, 2008) has a function of automatically stopping the movement of the apparatus when the apparatus is too close to the cornea, and a function of notifying (with a display or an alarm) that the apparatus is too close to the cornea.
In the eye-refractive-power measurement and the corneal-shape measurement, the working distances are relatively long. Therefore, the abovementioned safety measurements are not taken in general.
It is also possible to configure the measuring unit to move at a high speed in order to reduce a time for switching between the right and left eyes. However, if the weight of the measuring unit, etc. is taken into consideration, the safety in the subject may be lowered by decrease of the accuracy of the operation of moving the measuring unit, and the subject may feel anxious or surprised due to the sound generated during the movement.
In the ophthalmologic apparatus capable of executing a plurality of examinations, the following problems arise even when the aforementioned conventional art is incorporated.
First, the ophthalmologic apparatus described in JP-A 2007-282671 automatically moves the tonometry part toward the eye when shifting from the measurement of the eye refractive power, etc., to the measurement of the ocular tension (i.e., when moving the measuring head in the vertical direction). Consequently, the tonometry part is placed 24 mm (subtracting 11 mm from 35 mm) closer to the eye than the eye-refractive-power/corneal-shape measuring part.
Before executing the tonometry, it is required to align the tonometry part with the eye. During the alignment, the measuring head (tonometry part) may be moved in the anteroposterior direction. Here, if the movable range in the anteroposterior direction cannot be set as in the ophthalmologic apparatus described in JP-A 2007-282671, the nozzle may hit the eye. Specifically, the ophthalmologic apparatus of JP-A 2007-282671 can prevent contact with the eye when the measuring head is moved in the vertical direction, but cannot effectively prevent contact with the eye during the alignment.
Further, even if the technology of JP-A 2001-187024 or the CT-90A non-contact type tonometer described on the Internet (URL: http://www.topcon.co.jp/eyecare/pdf/ct—90a.pdf) by TOPCON Corporation in the online catalogue (retrieved on Feb. 6, 2008) is applied, it is necessary to manually set the movable range of the measuring head, whereby problems arise such as drop in examination efficiency and cumbersome operation. Specifically, when examining both the right and left eyes, it is necessary to set the movable range for each of the eyes. Further, there is concern that setting of the movable range is forgotten or setting of the movable range is omitted in favor of optimizing the examination efficiency.